1. Field of the Invention
The invention is in the general field of improved methods of pumping viscous hydrocarbons through a pipe, such as a well-bore or a pipeline.
2. General Background
The movement of heavy crudes through pipes is difficult because of their high viscosity and resulting low mobility. One method of improving the movement of these heavy crudes has included adding to the crude lighter hydrocarbons (e.g. kerosine distillate). This reduces the viscosity and thereby improves the mobility. This method has the disadvantage that it is expensive and the kerosine distillate is becoming difficult to obtain.
Another method of improving the movement of these heavy crudes is by heating them. This requires the installation of expensive heating equipment and thus is an expensive process.
The use of oil-in-water emulsions, which use surfactants to form the emulsion, is known in the art. While many surfactants serve to reduce the viscosity the effectiveness of various surfactants varies widely. Some surfactants are very effective, while others are barely effective. In fact such a wide variation is present in the effectiveness of surfactants that in general it can be concluded that the effectiveness of a particular surfactant, or combination of surfactants, is not predictable.
I have found that an aqueous solution of the following materials is effective in reducing the viscosity of viscous hydrocarbons: (a) an anionic alkyl polyether ethoxylated sulfate or (b) a combination of this material with an alcohol ether sulfate.